Method of coating articles by cathode disintegration



Sept. 23, 1941. B. BERGHAUS ETAQ. 2,256,771

METHOD OF COATING ARTICLES BY CATHODE DIS INTEGRATION Filed July 14, 1938 Sheets-Sheet 1 llllllllll I.

mf rl/arz I .Bfieghaus 7 9L lfmren oni Sept. 23, 1941-. B. BERGHAUS EI'AL. 2,256,771

METHOD OF COATING ARTICLES BY CATHODE DISINTEG'RATION Filed July 14,-1938 2 Sheets-Sheet 2 .3 Bar /7 a; Burg W025 Patented Sept. 23, 1941 UNITED STATE S PAT ENT OFFICE METHOD OF COATING ARTICLES BY CATHODE DISINTEGRATION Application July 14, 1938, Serial No. 219,293 In Germany August 14, 1937 4 Claims.

The present invention relates to a method of coating articles by means of particles disintegrated from a cathode.

It is known to coat metal articles by cathode disintegration, mainly by the disintegration of wires, bands or metal sheets, by means of an electric discharge, at pressures which are characteristic for the cathode disintegration. The disintegrated particles are spread uniformly in all directions and, in addition to being deposited on the articles, they are deposited also on the walls of the vessel and on the other constructional parts lying in the interior of the vessel. Only a comparatively small portion of the disintegrated material is deposited on the surface of the article to be coated, the remainder, deposited on the inner walls of the vessel and on the other parts being lost as regards further disintegration. The recovery of this material, more especially in the case of expensive materials such as silver, gold, platinum, rhodium, and the like, entails considerable expenditure and work. The object of the present invention is to avoid these disadvantages.

The invention relates to a method of coating articles by cathode disintegration, wherein the impinge either on the articles and the suspen-.

sion devices or on the wall of the vessel, where they take again part in the disintegration.

The cathode material deposited on the suspension devices, which are constructed in an easily removable manner and preferably consist of the materialto be disintegrated, can be easily recovered.

The anode voltage may be applied to the articles to be coated. Preferably,-however, the articles may be so connected as to carry a negative voltage with respect to the anode, and be surrounded by a. glow fringe. In this case a second conductor may be introduced in an insulated manner, provided with a replaceable disc-shaped electrode connected as an anode, which may consist of the material to be disintegrated.

The output on the surface of the articles per square centimeter is smaller than the load on the cathode-to be disintegrated. The load itself is to be coated consists. when use is made of alternating current voltage for the disintegration,

the source of alternating current voltage is connected preferably with the one terminal to the articles to be coated, and with the other ter-v minal to the-cathode to be disintegrated. Any

produced by thermionic tube generators, may

be used. In order to reduce the load on the articles with respect to that on the'cathode to be disintegratedregulating means, such as electric valves and resistances, are inserted in the connection from the transformer to the articles. In this way it is attained that the adjusted full output is supplied to the cathode, while the output on the articles can be reduced through the resistance.

Before the beginning of the disintegration of the cathode material, in the case of direct current, the article is first subjected to a preliminary disintegration, whereby it is attained that the material to be provided thereon will adhere especially firmly. In the case of alternating current disintegration the load on the article is higher than with respect to that on the cathode to be disintegrated, so that the surface of the articles is again cleaned before the coating thereof. Thereupon the disintegration conditions are so adjusted that materialis deposited on the articles. According to the material to be disintegrated, the vessel may be made solid of the cathode material, such as iron, copper, nickel, magnesium, aluminum and the like, but, in the case of expensive materials, such as silver, gold, platinum, rhodium, or of materials which have not suiiicient strength, such as cadmium, tin, zinc, or materials the shape of which cannot be changed, or only with difficulty changed, such as beryllium, chromium, titanium, molybdenum, tantalum, tungsten, the disintegration vessel may be coated with these materials on its inner wall. In the case of disintegration of materials up to a fusing point of about 1100? C., the miterial to be disintegrated may also be fused on the bottom of the vessel by heating with glow current and be disintegrated from the melt; The reduced pressures for'the disintegration may be adjusted-to lie between 10 and0.00l and preferably between 1.5 and 0.1 millimeters of mercury.

The invention will be more clearly understood by reference to the attached drawings and the dependent upon the material of which the article following detailed description wherein apparatus practice is dis- Figure 2 is a diagram of electric connections,' Figure 3 is another diagram of electric connections, and

Figure 4 is a third diagram of connections. Referring to Figure 1 which illustrates a sec- .13 is arranged in parallel circuit relation with tionthrough cathode disintegration apparatus,

the whole of the inner surface of the housing I forms a cathode which surrounds the articles to be coated. The. housing is closed in a vacuumtight manner by a cover 2 and a seal 3. The

1 whole inner space of the apparatus, that is to i say, the cover as well as the vessel, is coated 1 with material 4 to be disintegr ted, Which may consist of any desired metal,"-meta1 alloy or i 1 metalloid. The vacuum pump is connected to the connecting pipe 5, while the pipe connection I 6 serves for the introduction of a neutral, reducing gas,, such as hydrogen, nitrogen or the 1 like. The vessel is surrounded. by a jacket I to which a cooling medium, for instance water or l oil, is supplied by the pipe connection 8. The cooling medium is discharged through the pipe 1 connection 9. by clamps I 0 and may be conductively connected "to the vessel through the removable conductor H. The negative voltage is supplied by the cable l2 which is secured to the cover.

The cover is secured to the vessel The articles l3 to be coated are, for instance,

3 suspended on a frame I 4, which is secured to the lead-in conductor l5, connected through the cable 16, for instance, todirect current voltage.

Rings of insulating and sealing material are indicated at IL! and I9, and a metallic screen- 1 ing sleeve is provided, the hollow flange 2| of :which is clamped onto the cover by means of screws" which, for the sake of clearness, have i not been shown. The positive voltage is supplied to the screening sleeve through the cable 23. IThe screening sleeve 20 may be provided at its end with an anode 24 which may for instance be disc-shaped.

Also the cover of the vessel is provided with a jacket 25 to which the cooling medium is supplied-by. the pipe 26 and the cooling medium is discharged through a pipe connection 21.

, There is shown in Figure 2 a diagram of con-, snections which is, for instance, used in the in-' stallation according to Fig. 1. The source of direct current high voltage 58 is connected with the positive terminal thereof to the anode 24 overia resistance 60 and the negative terminal is connected over the switch 62 to the wall of the cathode disintegration housing I. The articles l3 are connected to a sliding contact of a resistance. 65, which is connected in parallel with thesource of direct current voltage.- The vac- :uum pump is represented at 65 and is connected over the valve 61 with the distintegration chamber, and a hydrogen flask H is connected over the valve 68 withfthe disintegration chamber,

The diagram of connections according toFig- .connected to the housing I.

use of an alternating current source 69 for carrying out the coating process. A transformer 10 is connected to the supply line 69 and one terminal of the secondary of this transformer is The other terminal of the secondary winding of the transformer is connected to thearticles I3 within the housing I through a rectifier 12. 'An adjustable resistor respect to the rectifier. The rectifier prevents the passage of current therethrough during one cycle so that the load of the disintegrating current can be regulated by the shunt resistor I3.

While the invention has been described in connection with specific types of apparatus it willbe appreciated that the coating method can be carried out with other structural arrangements and by following'various method steps. Such changes may'be made Without departing from the spirit and scope of the invention as set forth in the appended claims.

What we claim is:

1. The method of coating an article which comprises, surrounding the article to be coated with a housing having an inner surface formed of metallic material adapted to provide the coating for the article, sealing the housing, adjust ing the pressure within the housing to support cathode disintegration therein, and electrically disintegrating particles from all -points along the inner surface of said housing onto said article whereby the entire surface of the article is simultaneously coated.

2. The method of coating articles, which comprises, surrounding the articles to be coated with a housing having an inner surface formed of metallic material adapted to provide the coating for the articles, sealing the housing, adjusting the pressure within the housing to a range be-' tween 10 and 0.001 millimeters of mercury, and electrically disintegrating particles from all portions of the inner surface of said housing onto the articles whereby all surfaces of the articles ure 3 differs from the diagram of connections I according to Fig. 2 in that the articles l3 carry the positive voltage and are connected over the resistance to the positive terminal of the source of voltage 58.

The arrangement shown in Fig. 4 includesithe are simultaneously coated.

3. The method of coating articles which comprises, supporting the articles within a sealed housing having the inner surface completely. covered with a metal adapted to form the coating of the articles, adjusting the pressure within the housing to support cathode disintegration of the tegrating metal particles from all points of the imer surf-ace of the housing whereby some of the particles impinge onto the articles and other particles engage the inner surface of the housing for further disintegration.

4. The method of coating an article which comprises, supporting the article within a sealed housing having the inner surface formed of a metallic material for the coating and which completely surrounds the article, adjusting the pressure within the housing to support cathode dis integration of the inner surface of the housing, impressing a direct currentvoltage across the housing and an electrode within the housing with the housing connected negatively-with respect to said electrode to disintegrate particles from all 'points of the inner surface of the housing onto the article, andimpressing a voltage across said with respect to said electrode.

BERNHARD BERGHAUS. WILHELM BURKHARDT.

nected negatively inner surface of the housing, electrically disin- 

